Car washing apparatus

ABSTRACT

As a car moves along a predetermined path through a wash bay, it sequentially engages a pair of oppositely rotating brushes centrally disposed in its path. Each brush is suspended from a carriage which is axially movable along an overhead boom. The booms are pivotally mounted at their inner ends on opposite sides of the bay. The boom pivot axis is angularly oriented so that the boom is urged by gravity to the starting position with its outer free end inclined downwardly. Continued forward movement of the car swings the boom forwardly from the starting position to a retracted position to a retracted position beside the car&#39;&#39;s path. Frictional resistance between the brush and car causes the carriage to move axially towards the inner end of the boom while gravity maintains the brush in traction against the side of the car. As the car moves past the retracted brush, gravity urges the boom towards the starting position and the carriage is moved axially by gravity towards the free end of the boom. A hydraulic damper controls the rate at which the boom swings back towards the starting position to insure proper scrubbing of the rear of the car.

United States Patent 1 Shelstad 1 Nov. 20, 1973 CAR WASHING APPARATUS[76] Inventor: Richard J. Shelstadl, 3611 W. Normandy Ct., Mequon, Wis.

[22] Filed: June 15, 1972 [21] Appl. No.: 263,000

52 us. 01.; 15/21 D, 15/D1G. 2

[51] Int. Cl. B605 3/06 [58] Field of Search 15/DIGL 2, 21 D, 15/21 E,53

[56] References Cited UNITED STATES PATENTS 3,540,069 11/1970 Grant15/21 D 3,570,034 3/1971 Lanfrankie. 15/21 D 3,662,419 5/1972 Dini 15/21E FOREIGN PATENTS OR APPLICATIONS 1,951,067 10/1970 Germany l5/DIG. 2

Primary Examiner-Edward L. Roberts Attorney--John W. Michael et al.

57 ABSTRACT As a car moves along a predetermined path through a washbay, it sequentially engages a pair of oppositely rotating brushescentrally disposed in its path. Each brush is suspended from a carriagewhich is axially movable along an overhead boom. The booms are pivotallymounted at their inner ends on opposite sides of the bay. The boom pivotaxis is angularly oriented so that the boom is urged by gravity to thestarting position with its outer free end inclined downwardly. Continuedforward movement of the car swings the boom forwardly from the startingposition to a retracted position to a retracted position beside the carspath. Frictional resistance between the brush and car causes thecarriage to move axially towards the inner end of the boom while gravitymaintains the brush in traction against the side of the car. As the carmoves past the retracted brush, gravity urges the boom towards thestarting position and the carriage is moved axially by gravity towardsthe free end of the boom. A hydraulic damper controls the rate at whichthe boom swings back towards the starting position to insure properscrubbing of the rear of the car.

15 Claims, 8 Drawing Figures CAR WASHING APPARATUS BACKGROUND OF THEINVENTION This invention relates to car washing apparatus and, moreparticularly, to wrap-around brush assemblies therefor.

Automatic car washing apparatus typically employs a pair of verticalrotary brushes, carried on an overhead arm, which scrub the front, sidesand back of the car. The arms are positioned in sequential order onopposite sides of a bay through which the car is driven or moved by aconveyor. As the car passes through the bay, the arms are moved so thateach of the brushes first scrub laterally and outwardly from the centerof the car, then longitudinally along the side, and finally laterallyand inwardly back to the center of the car.

Various means have been employed to provide a controlled movement of theoverhead arms. For example, U.S. Pat. No. 3,350,733 describes arelatively elaborate hydraulic system, including various valving andcontrolling devices, for controlling the movement of the arms. Inaddition to requiring a large area for installation, and being expensiveto fabricate, devices of this type require frequent maintenance and partreplacement because of the large number of moving parts. U.S. Pat. No.3,570,034 describes an arrangement of springs, pulleys and weights forcontrolling the movement of the arms. Although having fewer movingparts, devices of this type require considerable supporting structure,making installation relatively expensive. U.S. Pat. No. 3,626,537describes the use of articulated arms which are operated by gravity.Devices of this type are considerably less complex in the other twodiscussed above; however, several moving components are still required.

SUMMARY OF THE INVENTION The primary object of this invention is toprovide a car washing'apparatus having a simplified wrap-around brushassembly which can be controlled with a minimum of moving parts and,thus, has reduced fabrication and maintenance costs.

Another object of this invention is to provide such a brush assemblywhich requires a relatively small space for installation and operation.

The car washing apparatus of this invention includes an overhead boompivoted at its inner end about a fixed pivot axis positioned at one sideof the car's path. In the starting position, the boom extendstransversely of this cars path, preferably at about a angle to the pathin the forward direction, and is pivotable from this starting positionto a retracted position generally parallel to the cars path. A carriage,from which a vertical rotary brush is suspended, is axially movablealong the boom. The boom is inclined downwardly toward its outer freeend so that the carriage is biased by gravity towards a neutralposition, disposed substantially in the center of the cars path when theboom is in the starting position. The pivot axis for the boom isarranged at a slight angle to the vertical to provide this incline andto provide a gravity bias urging the boom toward the starting position.

As a car moves along its predetermined path, it contacts the brush andswings the free end of the boom toward the retracted position. Thefrictional resistance between the rotating brush and the car providesthe necessary traction to obtain the desired scrubbing action along thefront of the car. As the car advances, this frictional resistance causesthe carriage to move axially along the boom thereby moving the brushrearwardly along the side of the car. As the rear comer of the car movespast the brush, the boom is urged by gravity to swing toward thestarting position, enabling the carriage to be moved by gravity towardthe neutral position so that the brush scrubs the rear of the car.Preferably, control means is provided to control the rate at which theboom returns toward the starting position so that a substantiallyconstant force is maintained between the brush and the car. A springloaded carriage stop menas can be provided on the outer end of the boomwhich permits the carriage to be released a predetermined distance pastthe neutral position, in the event the brush engages a larger thannormal projection on the front of the car.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top plan view of thewrap-around brush assembly of this invention, shown in the normallyextended and retracted positions.

FIG. 2 is a side elevational view of the brush assembly of FIG. 1.

FIG. 3 is a fragmentary, detailed view taken along the plane designated33 in FIG. 2.

FIGS. M are diagrammatic plan views of the brush assemblies illustratingtheir different positions as a car moves through the wash bay.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The car washing apparatus ofthis invention includes a pair of oppositely rotating, wrap-around brushassemblies which brush the right and left sides of a car as it movesalong the predetermined path through a wash bay. The car is either movedthrough the bay by a conventional conveyor means or driven through, withthe wheels being guided in wheel guides in a conventional manner. Thetwo wrap-around brush assemblies, which are located sequentially onopposite sides of the bay, are arranged in substantially the samemanner. Therefore, only the brush assembly located on the left side ofthe automobile (i.e. the drivers side) is illustrated in detail in FIGS.1-3.

Referring to FIGS. 1 and 2, each wrap-around brush assembly 10 includesan overhead boom 12 mounted on a vertical standard 14 located at theside of the wash bay. Boom 12 carries carriage 16, which is axiallymovable along the boom and from which a rotary vertical brush 18 issuspended. As shown in dashed lines in FIG. 1, boom 12 extendstransversely of the washing bay at a 45 angle to the path of the car(designated by arrow 20) when in the starting position shown by dashedlines in FIG. 1. Carraige 16 is biased (by gravity as explained below)to neutral position on the outer end of boom 12, disposing brush l8centrally in path 20.

Carriage 16 has a plurality of rollers 22, M, 26 which engage and rollalong the top, bottom and sides of the boom, respectively. These rollersare arranged to hold the carriage captive against the rocking forcesimposed thereon when a car strikes brush 1% as it moves through thewashing bay. These rollers are mounted on concentric shafts, which areadjustably mounted on the carriage so that the rollers can be adjustedinto and away from engagement with the boom. Thus, the rollers can beadjusted to obtain good rolling engagement with the boom at the time ofinitial installation of the carriage and during use as the rollers wear.The inward movement of carriage 16 along boom 12 is limited byspringloaded stop pin 28 which extends transversely through slots 29provided in the sides of the boom near the inner end thereof. Theoutward movement of carriage 16 along boom 12 is limited by aspring-loaded stop pin 30, which extends transversely through slots 32provided in the sides of the boom near the outer end thereof.

Brush 18 is mounted on a vertical drive shaft 36, which is driven byhydraulic motor 38. Brush 18 is of conventional design having flexiblebristles which are flailed outwardly by centrifugal force to impinge onand wipe the car body with a scrubbing action. The brush of the assemblylocated on the drivers side of the automobile (the one shown in FIGS. 1and 2) rotates in a counterclockwise direction, while the brush of theassembly located on the passenger side of the automobile rotates in aclockwise direction. Motor 38 is connected to a source of hydraulicfluid (not shown) by hoses 40 and 42. If desired, motor 38 can be aconventional electric motor, in which case an electrical cable(connected to a suitable source of electrical power) is used in place ofhydraulic hoses 40 and 42. Detergent is sprayed onto brush 18 by nozzle43, the upper end of which is mounted on carriage 16. Detergent issupplied to nozzle 43 by hose 44. The outlet head of nozzle ispreferably adjustable so that detergent can be sprayed onto the brush,directly onto the car, or both.

Boom 12 has a vertical shaft 46 located near its inner end which acts asits pivot axis. The upper and lower ends of shaft 46 are journaled inself-aligning, antifriction bearing 48 and 50, respectively. Bearings48, 50 are mounted to the outer ends of horizontal arms 52 and 54,respectively, which are located on the top portion of support standard14. Arms 52 and 54 are positioned generally parallel to the longitudinalaxis of car path 20. These arms extend outwardly from vertical standard14 so that brush 18 will not strike the vertical standard when carriage16 is moved against stop pin 28. Upper bearing 48 is bolted to end plate56 on upper arm 52 and lower bearing 50 is bolted to end plate 58 onlower arm 54.

As shown in FIG. 3, lower end plate 50 has elongated slots 60 throughwhich the lower bearing mounting bolts are installed. Slots 60 permitlower bearing 50 to be shifted transversely to the right with respect tothe upper bearing 48 (as viewed in FIG. 3) so that the longitudinal axisof shaft 46 is at a small angle to the vertical (e.g. about 4.5degrees). With shaft 46 so oriented, the longitudinal axis of boom 12 issubstantially horizontal, when it is in a retracted position, generallyparallel to path 20 (shown by the solid lines in FIG. 1 The boominclines downwardly toward its outer-free end in the starting position.Lower bearing 50 is adjusted to provide boom 12 with a sufficientincline so that carriage 16 is moved by gravity toward the neutralposition, as the boom swings from the retracted position towards thestarting position. Also, this angular orientation of the boom pivot axiscreates a gravity bias urging the boom toward the starting position.

As shown in FIG. 3, shaft 46 is preferably arranged to extend throughthe boom at a slight angle to the vertical. When so arranged, thetransverse axis of the boom remains substantially parallel with thefloor to it swings back and forth. This permits the carriage to rollfreely on the boom and provides uniform wearing of the rollers and theboom surface because of the uniform bearing load of the carriage on theboom. Also, the vertical axis of the brush is maintained substantiallyperpendicular and generally parallel to the side of the car, therebyproducing a uniform scrubbing action. If shaft 46 is arrangedvertically, the surfaces of the boom are tilted and the carriage isslightly cocked from the vertical. The resultant unbalanced bearing loadinhibits carriage movement to some degree and causes nonuniform wearingof the rollers and the surfaces of the boom.

A vertical plate 62 is mounted on the bay side of arms 52 and 54. Rods64 extends through an opening in plate 62 and has a rod end bearing 66at one end which is pivotally mounted on the inner end of boom 12 viapin 68. Boom 12 is partially biased to the starting position by coilspring 70, which is guided on one end of rod 64 and bears against oneside of plate 62, and coil spring 72, which is held on the opposite endof rod 64 by retainer 74 and bears against the otherside of plate 62.

A conventional hydraulic cylinder motion damper 76, connected betweenboom 12 and plate 62, controls the rate in which the boom swings back tothe starting position during the brushing operation. Damper 76 hasconventional fluid flow control means which provides substantiallyunrestricted flow during extension of the piston rod 72 (as the boomswings towards the retracted position) and restricts the fluid flow tocontrol the retraction rate of the piston rod (as the boom is swung backtoward the starting position). Outrigger bracket 80, mounted on anddepending outwardly from the side of boom 12, holds hydraulic hoses 40,42 and detergent supply hose 44 away from the brush so they do notbecome entangled therewith as the carriage travels back and forth on theboom during the brushing operation.

As mentioned above, the wrap-around brush assemblies are located onopposite sides of the washing bay and are situated so they are engagedsequentially by a car moving through the bay. As shown in FIGS. 4-8, theassemblies are positioned so that car 82 first contacts assembly 10Alocated on the driver's side. Upon initial contact by car 82, brush 18,driven counterclockwise by motor 38, commences scrubbing the front ofthe automobile. The brush moves from the center toward the left frontcorner, as boom 12 is swung toward the retracted position by the forwardmovement of car 82. As the left front comer of the car moves past thebrush (with the boom in the retracted position), springloaded stop pin30 allows carriage 16 to move further toward the outer end of the boom,in the event the brush encounters a larger-than-normal projection, suchas a protruding headlight or the like.

As the boom swings to the retracted position, spring is compressed toaccept the thrust and prevents the brush from bouncing, thereby insuringthe brush does not miss scrubbing a portion of the front fender. Afterthe left front corner of the car has advanced past the brush, thefrictional resistance between the rotating brush and the car tends tomove carriage 16 axially along boom 12 toward its inner end as shown inFIG. 5. Spring-loaded stop 28 limits the inward movement of the carriagewith its spring absorbing the thrust of the carriage. The combination ofthe gravity bias on the boom produced by its non-vertical pivot axis,and the biasing force of spring 70 maintains the brush against the sideof the automobile with sufficient traction to provide the desiredscrubbing action as the car advances.

By the time the left rear corner of car 82 advances past the retractedbrush, boom 12 has been urged by gravity generally to its startingposition as shown in FIG. 6. The rate at which the boom returns towardthe starting position is controlled by motion damper 76 so thatsubstantially uniform and constant pressure is maintained between thebrush and the car. Carriage 16 is then moved toward its neutral positionby the combination of gravity and the frictional resistance between thebrush and the car as shown in FIG. 7. Spring 72 prevents the brush frombouncing away from the rear of the car as the carriage travels towardthe neutral position. Spring '72 also compresses to allow the brush togo past the center of the automobile. Upon decompression, spring 72repositions the boom to the starting position so a portion of the rearof the car is rescrubbed.

When car 82 reaches the position shown in FIG. 7, the brush of assemblyB is engaged. The brush, driven clockwise by motor 38, commencesscrubbing the right side of the car in the same manner as describedabove. ln a practice, the relative location of the brush assembliesalong the wash bay can be closer together, so that brush assembly 108 isengaged and commences scrubbing the car prior to reaching the positionshown in FIG. 7. Assemblies 10A and 10B are preferably arranged so thebrushes extend slightly past the center of path 20, when in the startingposition. This provides some overlap of scrubbing and insures completecoverage.

From the above description, it can be appreciated that the car washingapparatus of this invention is arranged so that movement of thewrap-around brush is controlled with a minimum of moving parts. Theprimary motivation of the brush is provided by the traction of the brushitself and by gravity, which maintains the brush in traction against thecar body, returns the boom to its starting position, and returns thecarriage to its neutral position. Thus, the need for elaborate,expensive and high maintenance controls is not required to attainsatisfactory brush operation and assure the brush closely follows thecontour of the ear. The free standing unit, although sturdy inconstruction, does not require a structural housing and is economical tofabricate. Furthermore, minimum space is required to accommodatemovement of the overhead arm.

As will be readily apparent to those skilled in the art, upon readingthe above detailed description of a preferred embodiment of thisinvention, various modifications and alterations can be made theretowithout departing from the spirit and scope thereof.

I claim:

1. Car washing apparatus for scrubbing the front, one side, and rear ofa car body as it moves along a predetermined path comprising:

an overhead boom pivoted at its inner end about a fixed axis positionedat one side of said path and 7 having an outer free end, said boomextending transversely of the path and inclining downwardly towards itsfree end when in a starting position and being pivotable between thestarting position and a retracted position generally parallel to thepath;

biasing means for biasing said boom toward the starting position;

a carriage axially movable along said boom, said carriage being biasedby gravity toward a neutral position near the free end of said boom anddisposed substantially centrally in the path;

a rotary vertical brush suspended from said carriage;

and

means for rotating said brush in a direction such that, upon beingcontacted by a car moving along the path, the contact between saidrotating brush and the car causes the free end of said boom to swingforwardly toward the retracted position until said brush reaches thefront corner of the car, then moves said carriage axially along saidboom with said brush moving rearwardly along the side of the car towardthe rear corner thereof as said biasing means urges said boom to swingtoward the starting position, and after the rear comer of the car movespast said brush, said carriage is moved by gravity axially back alongsaid boom toward the neutral position with said brush moving along therear of the car.

2. The car washing apparatus according to claim 1 wherein said biasingmeans includes means for positioning the pivot axis, so the pivot axisis displaced from the perpendicular outwardly from the car at its lowerend to provide the downward incline of said boom when said boom is inthe starting position, and to provide a gravity bias urging said boomtoward the starting position.

3. The car washing apparatus according to claim 2 wherein said boom hasa transverse axis and a carriage support surface means thereon, and saidcarriage has a roller means therein in engagement with said carriagesupport surface means, said displaced pivot axis of said boom positionedwith respect to the transverse axis of said boom so as to provide auniform bearing load between said roller means and said carriage supportsurface means to thereby provide uniform wearing of said roller meansand said carriage support surface means.

4. The car washing apparatus according to claim 3 wherein saidpositioning means includes a laterally shiftable journal means carryingthe pivot axis.

5. The car washing apparatus according to claim 4'. including a supportmeans positioned at one side of the path and carrying said journalmeans, said journal means mounted on said support means so that thelongitudinal axis of said boom is substantially horizontal when in theretracted position.

6. The car washing apparatus according to claim 1 including controlmeans which permits substantially free movement of said boom toward theretracted position and controls the rate at which said boom swings backtoward the starting position from the retracted position, so that asubstantially constant force is maintained between said brush and thecar.

7. The car washing apparatus according to claim 6 wherein said controlmeans includes a fluid cylinder connected to said boom, said cylinderincluding a piston and a fluid control means which controls fluid flowto one side of said piston so it can move freely in one direction assaid boom moves toward the retracted position and limits fluid flow tothe other side of said piston so it moves at a controlled rate in theopposite direction as said boom swings back toward the startingposition.

b. The car washing apparatus according to claim 1 including a verticalstandard positioned at one side of said path and carrying the pivot axisand wherein said biasing means includes a vertical plate mounted on saidstandard; a rod means slidably extending through an opening in saidplate and including a first end pivotally mounted to the inner endportion of said boom and a second end extending through the opening;

a first spring means carried on a first end of said rod means whichbears against one side of said plate and is compressed as said boommoves towards the retracted position; and

a second spring carried on a second end of said rod means which bearsagainst the opposite side of said plate and is compressed as said boomswings back past the starting position.

9. The car washing apparatus according to claim 3 wherein said boom isdisposed forwardly in the direction of the car movement at an angle ofapproximately 45 to the path when in the starting position.

10. The car washing apparatus according to claim 1 including aspring-loaded carriage stop means positioned near the outer end of saidboom which is normally engaged by said carriage when in the neutralposition for permitting said carriage to move axially along said boom apredetermined distance from the neutral position in the event said brushengages a larger than normal projection on the front of the car.

11. Car washing apparatus for scrubbing the front, one side and rear ofa car body as it moves along a predetermined path comprising:

a support means positioned at one side of the path;

an overhead boom pivoted at its inner end about a fixed axis carried bysaid support means and having a free outer end, said boom extendingtransversely of the path and inclining downwardly towards its free endwhen in a starting position and being pivotable between the startingposition and a retracted position generally parallel to the path;

means for positioning said pivot axis with its lower end displaced fromthe perpendicular outwardly from the car to provide the downward inclineof said boom and to provide a gravity bias urging said boom toward thestarting position;

a carriage axially movable along said boom, said carriage being biasedby gravity towards a neutral position near the free end of said boom anddisposed substantially centrally in the path;

a rotary vertical brush suspended from said carriage;

and

means for rotating said brush in a direction such that,

upon being contacted by a car moving along the path, the contact betweensaid rotating brush and the car causes the free end of said boom toswing forwardly towards the retracted position until said brush reachesthe front comer of the car, then moves said carriage axially along saidboom with said brush moving rearwardly along the side of the car towardsthe rear corner thereof as said boom is urged by the gravity bias towardthe starting position, after the rear comer of the car moves past saidbrush, said carriage is moved by gravity axially back along said boomtoward the neutral position with said brush moving along the rear of thecar.

12. The car washing apparatus according to claim 1 1 wherein said boomhas a transverse axis and a carriage support surface means thereon, andsaid carriage has roller means thereon in engagement with said carriagesupport surface means, said displaced pivot axis of said boom positionedwith respect to the transverse axis of said boom so as to provide auniform bearing load between said roller means and said carriage supportsurface means to thereby provide uniform wearing of said roller meansand said carriage support surface means.

13. The car washing apparatus according to claim 12 including aspring-loaded carriage stop means positioned near the outer end of saidboom which is normally engaged by said carriage when in the neutralposition and permits said carriage to move outwardly along said boom apredetermined distance from the neutral position in the event said brushengages a larger than normal projection on the front of the car.

14. The car washing apparatus according to claim 1 1 wherein said boomis disposed forwardly in the direction of the car movement at an angleof approximately 45 to the path when in the starting position.

15. The car washing apparatus according to claim 14 including controlmeans which permits substantially free movement of said boom towards theretracted position and controls the rate at which said boom swings backtowards the Starting position from the retracted position so that asubstantially constant force is maintained between said brush and thecar.

i i i

1. Car washing apparatus for scrubbing the front, one side, and rear ofa car body as it moves along a predetermined path comprising: anoverhead boom pivoted at its inner end about a fixed axis positioned atone side of said path and having an outer free end, said boom extendingtransversely of the path and inclining downwardly towards its free endwhen in a starting position and being pivotable between the startingposition and a retracted position generally parallel to the path;biasing means for biasing said boom toward the starting position; acarriage axially movable along said boom, said carriage being biased bygravity toward a neutral position near the free end of said boom anddisposed substantially centrally in the path; a rotary vertical brushsuspended from said carriage; and means for rotating said brush in adirection such that, upon being contacted by a car moving along thepath, the contact between said rotating brush and the car causes thefree end of said boom to swing forwardly toward the retracted positionuntil said brush reaches the front corner of the car, then moves saidcarriage axially along said boom with said brush moving rearwardly alongthe side of the car toward the rear corner thereof as said biasing meansurges said boom to swing toward the starting position, and after therear corner of the car moves past said brush, said carriage is moved bygravity axially back along said boom toward the neutral position withsaid brush moving along the rear of the car.
 2. The car washingapparatus according to claim 1 wherein said biasing means includes meansfor positioning the pivot axis, so the pivot axis is displaced from theperpendicular outwardly from the car at its lower end to provide thedownward incline of said boom when said boom is in the startingposition, and to provide a gravity bias urging said boom toward thestarting position.
 3. The car washing apparatus according to claim 2wherein said boom has a transverse axis and a carriage support surfacemeans thereon, and said carriage has a roller means therein inengagement with said carriage support surface means, said displacedpivot axis of said boom positioned with respect to the transverse axisof said boom so as to provide a uniform bearing load between said rollermeans and said carriage support surface means to thereby provide uniformwearing of said roller means and said carriage support surface means. 4.The car washing apparatus according to claim 3 wherein said positioningmeans includes a laterally shiftable journal means carrying the pivotaxis.
 5. The car washing apparatus according to claim 4 including asupport means positioned at one side of the path and carrying saidjournal means, said journal means mounted on said support means so thatthe longitudinal axis of said boom is substantially horizontal when inthe retracted position.
 6. The car washing apparatus according to claim1 including control means which permits substantially free movement ofsaid boom toward the retracted position and controls the rate at whichsaid boom swings back toward the starting position from the retractedposition, so that a substantially constant force is maintained betweensaid brush and the car.
 7. The car washing apparatus according to claim6 wherein said control means includes a fluid cylinder connected to saidboom, said cylinder including a piston and a fluid control means whichcontrols fluid flow to one side of said piston so it can move freely inone direction as said boom moves toward the retracted position andlimits fluid flow to the other side of said piston so it moves at acontrolled rate in the opposite direction as said boom swings backtoward the starting position.
 8. The car washing apparatus according toclaim 1 including a vertical standard positioned at one side of saidpath and carrying the pivot axis and wherein said biasing means includesa vertical plate mounted on said standard; a rod means slidablyextending through an opening in said plate and including a first endpivotally mounted to the inner end portion of said boom and a second endextending through the opening; a first spring means carried on a firstend of said rod means which bears against one side of said plate and iscompressed as said boom moves towards the retracted position; and asecond spring carried on a second end of said rod means which bearsagainst the opposite side of said plate and is compressed as said boomswings back past the starting position.
 9. The car washing apparatusaccording to claim 3 wherein said boom is disposed forwardly in thedirection of the car movement at an angle of approximately 45* to thepath when in the starting position.
 10. The car washing apparatusaccording to claim 1 including a spring-loaded carriage stop meanspositioned near the outer end of said boom which is normally engaged bysaid carriage when in the neutral position for permitting said carriageto move axially along said boom a predetermined distance from theneutral position in the event said brush engages a larger than normalprojection on the front of the car.
 11. Car washing apparatus forscrubbing the front, one side and rear of a car body as it moves along apre-determined path comprising: a support means positioned at one sideof the path; an overhead boom pivoted at its inner end about a fixedaxis carried by said support means and having a free outer end, saidboom extending transversely of the path and inclining downwardly towardsits free end when in a starting position and being pivotable between thestarting position and a retracted position generally parallel to thepath; means for positioning said pivot axis with its lower end displacedfrom the perpendicular outwardly from the car to provide the downwardincline of said boom and to provide a gravity bias urging said boomtoward the starting position; a carriage axially movable along saidboom, said carriage being biased by gravity towards a neutral positionnear the free end of said boom and disposed substantially centrally inthe path; a rotary vertical brush suspended from said carriage; andmeans for rotating said brush in a direction such that, upon beingcontacted by a car moving along the path, the contact between saidrotating brush and the car causes the free end of said boom to swingforwardly towards the retracted position until said brush reaches thefront corner of the car, then moves said carriage axially along saidboom with said brush moving rearwardly along the side of the car towardsthe rear corner thereof as said boom is urged by the gravity bias towardthe starting position, after the rear corner of the car moves past saidbrush, said carriage is moved by gravity axially back along said boomtoward the neutral position with said brush moving along the rear of thecar.
 12. The car washing apparatus according to claim 11 wherein saidboom has a transverse axis and a carriage support surface means thereon,and said carriage has roller means thereon in engagement with saidcarriage support surface means, said displaced pivot axis of said boompositioned with respect to the transverse axis of said boom so as toprovide a uniform bearing load between said roller means and saidcarriage support surface means to thereby provide uniform wearing ofsaid roller means and said carriage support surface means.
 13. The carwashing apparatus according to claim 12 including a spring-loadedcarriage stop means positioned near the outer end of said boom which isnormally engaged by said carriage when in the neutral position andpermits said carriage to move outwardly along said boom a predetermineddistance from the neutral position in the event said brush engages alarger than normal projection on the front of the car.
 14. The carwashing apparatus according to claim 11 wherein said boom is disposedforwardly in the direction of the car movement at an angle ofapproximately 45* to the path when in the starting position.
 15. The carwashing apparatus according to claim 14 including control means whichpermits substantially free movement of said boom towards the retractedposition and controls the rate at which said boom swings back towardsthe starting position from the retracted position so that asubstantially constant force is maintained between said brush and thecar.